Further studies on GSH-S-transferases to see if they all show GSH-organic nitrate ester reductase activity (GSH-ONER). Characterization of inhibitor action on purified GSH-S-transferases and GSH-ONER activity. Further study of the in vivo inhibition of glyceryl trinitrate metabolism in rat and guinea pig by GSH-S-transferase inhibitors. Examination of tissues where prostaglandin metabolism occurs to see if the GSH-peroxidase activity and the prostaglandin isomerase activity of GSH-S-transferases is functional at such sites.